"Show me just what Mohammed brought that was new, and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached." - Manuel II Palelologus
Actually, it's similar to jury nullification. A jury has the unchallengeable power to decide guilt or innocence, for any reason they like.
And a President has the unchallengeable power to pardon or commute a sentence--for any reason he prefers, or for no reason at all.
And the House has the unchallengeable power to impeach, and the Senate the power to convict--for any reason they prefer, or for no reason at all.
And the only recourse the people would have would be to vote the rascals out at the next election.
I think you just answered your own question. ;-)